This invention relates to a vehicle seat assembly having an inflatable bladder in the seat to provide adjustable support for the seat occupant and in particular to an improved air delivery system for inflating and deflating the seat bladder having a single, non-reversible pump for both inflating and deflating the bladder.
It is well known in the art to provide inflatable bladders in vehicle seat assemblies for enabling the seat occupant to adjust the support provided by the seat as desired. Seat bladders are generally inflated by either a hand actuated pump or by an electric motor driven pump. The bladders are often deflated simply by venting the bladder to the atmosphere. To sufficiently deflate the bladder, it is generally necessary for the seat occupant to apply pressure to the bladder. Depending upon the location of the bladder within the seat assembly, it can be cumbersome for the occupant to apply the necessary pressure to fully deflate the bladder.
Accordingly, air delivery systems have been developed which utilize a pump to deflate the bladder. One way to deflate the bladder with a pump is to provide a second pump. In such a system, there is one pump dedicated to inflating the bladder and a second pump dedicated to deflating the bladder. Alternatively, a single reversible pump can be used to both inflate and deflate the bladder as described in U.S. Pat. No. 4,707,027 With a reversible pump, the air flow direction through the pump is reversed by a control switch. Both of these systems which use a pump to deflate the bladder, have their disadvantages. The two pump system has the added expense of the second pump. A reversible pump is more expensive than a one-directional pump and is less efficient. Because it is less efficient, a larger motor is required to produce the same amount of air pressure and volume flow as a one-directional pump.
Accordingly, it is an object of the present invention to provide a vehicle seat having an inflatable bladder with a single, one-directional pump for both inflating and deflating the bladder.
It is an advantage of the present invention that the air delivery system cost is reduced by use of a single, one-directional pump versus two pumps or a reversible pump.
It is a further advantage of the present invention, that the pump efficiency of a one-directional pump is greater than the efficiency of a reversible pump.
The air delivery system of the present invention utilizes a single, one-directional pump to both inflate and deflate the bladder. The pump outlet is connected to the bladder through a pump outlet conduit while the pump inlet is connected to the bladder through a pump inlet conduit. One or more valves are used to selectively connect the pump outlet to the bladder for inflating the bladder and to selectively connect the pump outlet to atmosphere when the bladder is being deflated. Likewise, one or more valves are provided in the pump inlet conduit to selectively connect the pump inlet to the bladder for deflating the bladder and to selectively connect the pump inlet to atmosphere for inflating the bladder.
The air delivery system also includes an electrical control circuit for operating the valves and the motor used to drive the pump. The control circuit includes a single pull, double throw switch which is open in the rest position. When the switch is moved to one closed position, the motor is energized and the appropriate valves are opened to communicate the pump outlet to the bladder and the pump inlet to atmosphere. In the other closed position of the switch, the motor is energized and the appropriate valves are opened to connect the pump inlet to the bladder and the pump outlet to atmosphere for deflating the bladder.
The air delivery system may include one or more spring biased check valves which are normally closed instead of electrically actuated valves. The check valves are opened by air pressure or vacuum from the pump to allow air flow therethrough.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.